Originally posted by rcavictim
You must like the Heil. It sure is a massive slugger. I've never seen one in person or heard it. Does it vent out the back like a dipole or is it front only like a horn? How low can you cross it over?

They are a nice tweeter -- and relatively cheap ($300 or so a pr from ESS as spare parts IB -- we've not actually sourced one that way). This particular Heil is a dipole, there are smaller monopole ones.

XO on these is around 2k (1st order on the 2-ways -- driven by mono Decware ZENs).

I believe I heard the Heil drivers on AMT speakers long ago. How long have they been around? When I heard them, I was blown away by the transparent sound of them. I could hear the pick contacting the guitar string as it was struck. Amazing.
I have never heard anything as clear since. Is there a downside to these speakers? Narrow dispersion?

Originally posted by PELarson
Just did some elementary googling to answer my own questions. Yes, long ago: 1973 was when the Heil drivers were introduced. Where can I acquire some of these drivers?

downside is trying to find something good enuff to keep up... these can be had new as spare parts from ESS in CA (~$300 USD/pr i was told)-- there is also a European licencee, don't know if you can get the driver by itself thou (shipping from CA would be a lot easier to handle as well). And there is always used (off eBay or such)

I just bought a pair of these from ESS for $300 and would like to know some specs. Do you have any sensitivity info or graphs? My plan is to mate them with a pair of woofers from a Klipsch RF-7 that have about 99 db/w/m and built to keep up with a horn mid-tweet. Objective is to build high efficiency speakers without LARGE enclosures or horns.